@poketrade mentioned them about a month ago in his upcoming English promos thread: www.elitefourum.com/t/newest-various-english-promo-releases-thread/23216/1. They come with the DVD/Blue-Ray of the Detective Pikachu movie. Didn’t knew they were already available for sale through, since I’m looking forward to them.
There will also be a stamped variation of the SM170 Pikachu.
Both are supposed to be released in September, though. So not sure why that seller already has them right now. 
Greetz,
Quuador